To achieve high-efficient power conversion, application of power electronics and power semiconductor development are actively carried out. To handle wide rated voltages and currents, various elements have been developed. Use purposes and elements to be used are determined depending on switching frequencies and power capacities. As representative elements, there are semiconductor devices such as metal oxide semiconductor field effect transistors (MOSFET) suitable for high-frequency operations and insulated gate bipolar transistors (IGBT), which are bipolar elements capable of high breakdown resistance and large current capacity, and pin diodes. In such semiconductor devices, operability, high breakdown resistance, and the like are necessary along with low-loss driving, and thus a high breakdown resistance design is an important design factor.